A Thermal Diffusivity Measuring Apparatus with PC based Data Acquisition and Processing

摘要

Angstrom devised a method for the measurement of thermal diffusivity of small dimension samples. This method has been used globally to measure thermal diffusivity of rocks/minerals/carbon-fibers/composites etc. by incorporating suitable modifications in the system. In this technical note we describe an apparatus, designed, fabricated and tested at the National Geophysical Research Institute, to measure thermal diffusivity of rock samples. The apparatus has been designed using microprocessor based signal conditioners for the acquisition of temperature data with advantage of signal stacking and linearization with the help of stored look up tables. PC based user interface was incorporated for data acquisition, data playback and data processing. An important feature of data processing software is to automatically compute waveform amplitudes and phase differences even when the waveforms are not ideal sine waves. The performance of this instrument was verified by determining the thermal diffusivity of fused silica, corundum and comparing with the reported values.